There is no standard sizing, so you might take diiferent sizes from different manufacturers. This can be a problem with on-line ordering.

Second, many companies offer jerseys in two basic cuts--a tighter-fitting, "racing" cut or a more relaxed fit, sometimes called something like "club fit." The former is "aerodynamic," to avoid flapping around; the latter is for us non-racers. <grin>

How tight should it fit? A matter of preference, eh? Personally, I hate snug-fitting clothing.